jerojasro@336: \chapter{Handling repository events with hooks}
jerojasro@336: \label{chap:hook}
jerojasro@336: 
jerojasro@336: Mercurial offers a powerful mechanism to let you perform automated
jerojasro@336: actions in response to events that occur in a repository.  In some
jerojasro@336: cases, you can even control Mercurial's response to those events.
jerojasro@336: 
jerojasro@336: The name Mercurial uses for one of these actions is a \emph{hook}.
jerojasro@336: Hooks are called ``triggers'' in some revision control systems, but
jerojasro@336: the two names refer to the same idea.
jerojasro@336: 
jerojasro@336: \section{An overview of hooks in Mercurial}
jerojasro@336: 
jerojasro@336: Here is a brief list of the hooks that Mercurial supports.  We will
jerojasro@336: revisit each of these hooks in more detail later, in
jerojasro@336: section~\ref{sec:hook:ref}.
jerojasro@336: 
jerojasro@336: \begin{itemize}
jerojasro@336: \item[\small\hook{changegroup}] This is run after a group of
jerojasro@336:   changesets has been brought into the repository from elsewhere.
jerojasro@336: \item[\small\hook{commit}] This is run after a new changeset has been
jerojasro@336:   created in the local repository.
jerojasro@336: \item[\small\hook{incoming}] This is run once for each new changeset
jerojasro@336:   that is brought into the repository from elsewhere.  Notice the
jerojasro@336:   difference from \hook{changegroup}, which is run once per
jerojasro@336:   \emph{group} of changesets brought in.
jerojasro@336: \item[\small\hook{outgoing}] This is run after a group of changesets
jerojasro@336:   has been transmitted from this repository.
jerojasro@336: \item[\small\hook{prechangegroup}] This is run before starting to
jerojasro@336:   bring a group of changesets into the repository.
jerojasro@336: \item[\small\hook{precommit}] Controlling. This is run before starting
jerojasro@336:   a commit.
jerojasro@336: \item[\small\hook{preoutgoing}] Controlling. This is run before
jerojasro@336:   starting to transmit a group of changesets from this repository.
jerojasro@336: \item[\small\hook{pretag}] Controlling. This is run before creating a tag.
jerojasro@336: \item[\small\hook{pretxnchangegroup}] Controlling. This is run after a
jerojasro@336:   group of changesets has been brought into the local repository from
jerojasro@336:   another, but before the transaction completes that will make the
jerojasro@336:   changes permanent in the repository.
jerojasro@336: \item[\small\hook{pretxncommit}] Controlling. This is run after a new
jerojasro@336:   changeset has been created in the local repository, but before the
jerojasro@336:   transaction completes that will make it permanent.
jerojasro@336: \item[\small\hook{preupdate}] Controlling. This is run before starting
jerojasro@336:   an update or merge of the working directory.
jerojasro@336: \item[\small\hook{tag}] This is run after a tag is created.
jerojasro@336: \item[\small\hook{update}] This is run after an update or merge of the
jerojasro@336:   working directory has finished.
jerojasro@336: \end{itemize}
jerojasro@336: Each of the hooks whose description begins with the word
jerojasro@336: ``Controlling'' has the ability to determine whether an activity can
jerojasro@336: proceed.  If the hook succeeds, the activity may proceed; if it fails,
jerojasro@336: the activity is either not permitted or undone, depending on the hook.
jerojasro@336: 
jerojasro@336: \section{Hooks and security}
jerojasro@336: 
jerojasro@336: \subsection{Hooks are run with your privileges}
jerojasro@336: 
jerojasro@336: When you run a Mercurial command in a repository, and the command
jerojasro@336: causes a hook to run, that hook runs on \emph{your} system, under
jerojasro@336: \emph{your} user account, with \emph{your} privilege level.  Since
jerojasro@336: hooks are arbitrary pieces of executable code, you should treat them
jerojasro@336: with an appropriate level of suspicion.  Do not install a hook unless
jerojasro@336: you are confident that you know who created it and what it does.
jerojasro@336: 
jerojasro@336: In some cases, you may be exposed to hooks that you did not install
jerojasro@336: yourself.  If you work with Mercurial on an unfamiliar system,
jerojasro@336: Mercurial will run hooks defined in that system's global \hgrc\ file.
jerojasro@336: 
jerojasro@336: If you are working with a repository owned by another user, Mercurial
jerojasro@336: can run hooks defined in that user's repository, but it will still run
jerojasro@336: them as ``you''.  For example, if you \hgcmd{pull} from that
jerojasro@336: repository, and its \sfilename{.hg/hgrc} defines a local
jerojasro@336: \hook{outgoing} hook, that hook will run under your user account, even
jerojasro@336: though you don't own that repository.
jerojasro@336: 
jerojasro@336: \begin{note}
jerojasro@336:   This only applies if you are pulling from a repository on a local or
jerojasro@336:   network filesystem.  If you're pulling over http or ssh, any
jerojasro@336:   \hook{outgoing} hook will run under whatever account is executing
jerojasro@336:   the server process, on the server.
jerojasro@336: \end{note}
jerojasro@336: 
jerojasro@336: XXX To see what hooks are defined in a repository, use the
jerojasro@336: \hgcmdargs{config}{hooks} command.  If you are working in one
jerojasro@336: repository, but talking to another that you do not own (e.g.~using
jerojasro@336: \hgcmd{pull} or \hgcmd{incoming}), remember that it is the other
jerojasro@336: repository's hooks you should be checking, not your own.
jerojasro@336: 
jerojasro@336: \subsection{Hooks do not propagate}
jerojasro@336: 
jerojasro@336: In Mercurial, hooks are not revision controlled, and do not propagate
jerojasro@336: when you clone, or pull from, a repository.  The reason for this is
jerojasro@336: simple: a hook is a completely arbitrary piece of executable code.  It
jerojasro@336: runs under your user identity, with your privilege level, on your
jerojasro@336: machine.
jerojasro@336: 
jerojasro@336: It would be extremely reckless for any distributed revision control
jerojasro@336: system to implement revision-controlled hooks, as this would offer an
jerojasro@336: easily exploitable way to subvert the accounts of users of the
jerojasro@336: revision control system.
jerojasro@336: 
jerojasro@336: Since Mercurial does not propagate hooks, if you are collaborating
jerojasro@336: with other people on a common project, you should not assume that they
jerojasro@336: are using the same Mercurial hooks as you are, or that theirs are
jerojasro@336: correctly configured.  You should document the hooks you expect people
jerojasro@336: to use.
jerojasro@336: 
jerojasro@336: In a corporate intranet, this is somewhat easier to control, as you
jerojasro@336: can for example provide a ``standard'' installation of Mercurial on an
jerojasro@336: NFS filesystem, and use a site-wide \hgrc\ file to define hooks that
jerojasro@336: all users will see.  However, this too has its limits; see below.
jerojasro@336: 
jerojasro@336: \subsection{Hooks can be overridden}
jerojasro@336: 
jerojasro@336: Mercurial allows you to override a hook definition by redefining the
jerojasro@336: hook.  You can disable it by setting its value to the empty string, or
jerojasro@336: change its behaviour as you wish.
jerojasro@336: 
jerojasro@336: If you deploy a system-~or site-wide \hgrc\ file that defines some
jerojasro@336: hooks, you should thus understand that your users can disable or
jerojasro@336: override those hooks.
jerojasro@336: 
jerojasro@336: \subsection{Ensuring that critical hooks are run}
jerojasro@336: 
jerojasro@336: Sometimes you may want to enforce a policy that you do not want others
jerojasro@336: to be able to work around.  For example, you may have a requirement
jerojasro@336: that every changeset must pass a rigorous set of tests.  Defining this
jerojasro@336: requirement via a hook in a site-wide \hgrc\ won't work for remote
jerojasro@336: users on laptops, and of course local users can subvert it at will by
jerojasro@336: overriding the hook.
jerojasro@336: 
jerojasro@336: Instead, you can set up your policies for use of Mercurial so that
jerojasro@336: people are expected to propagate changes through a well-known
jerojasro@336: ``canonical'' server that you have locked down and configured
jerojasro@336: appropriately.
jerojasro@336: 
jerojasro@336: One way to do this is via a combination of social engineering and
jerojasro@336: technology.  Set up a restricted-access account; users can push
jerojasro@336: changes over the network to repositories managed by this account, but
jerojasro@336: they cannot log into the account and run normal shell commands.  In
jerojasro@336: this scenario, a user can commit a changeset that contains any old
jerojasro@336: garbage they want.
jerojasro@336: 
jerojasro@336: When someone pushes a changeset to the server that everyone pulls
jerojasro@336: from, the server will test the changeset before it accepts it as
jerojasro@336: permanent, and reject it if it fails to pass the test suite.  If
jerojasro@336: people only pull changes from this filtering server, it will serve to
jerojasro@336: ensure that all changes that people pull have been automatically
jerojasro@336: vetted.
jerojasro@336: 
jerojasro@336: \section{Care with \texttt{pretxn} hooks in a shared-access repository}
jerojasro@336: 
jerojasro@336: If you want to use hooks to do some automated work in a repository
jerojasro@336: that a number of people have shared access to, you need to be careful
jerojasro@336: in how you do this.
jerojasro@336: 
jerojasro@336: Mercurial only locks a repository when it is writing to the
jerojasro@336: repository, and only the parts of Mercurial that write to the
jerojasro@336: repository pay attention to locks.  Write locks are necessary to
jerojasro@336: prevent multiple simultaneous writers from scribbling on each other's
jerojasro@336: work, corrupting the repository.
jerojasro@336: 
jerojasro@336: Because Mercurial is careful with the order in which it reads and
jerojasro@336: writes data, it does not need to acquire a lock when it wants to read
jerojasro@336: data from the repository.  The parts of Mercurial that read from the
jerojasro@336: repository never pay attention to locks.  This lockless reading scheme
jerojasro@336: greatly increases performance and concurrency.
jerojasro@336: 
jerojasro@336: With great performance comes a trade-off, though, one which has the
jerojasro@336: potential to cause you trouble unless you're aware of it.  To describe
jerojasro@336: this requires a little detail about how Mercurial adds changesets to a
jerojasro@336: repository and reads those changes.
jerojasro@336: 
jerojasro@336: When Mercurial \emph{writes} metadata, it writes it straight into the
jerojasro@336: destination file.  It writes file data first, then manifest data
jerojasro@336: (which contains pointers to the new file data), then changelog data
jerojasro@336: (which contains pointers to the new manifest data).  Before the first
jerojasro@336: write to each file, it stores a record of where the end of the file
jerojasro@336: was in its transaction log.  If the transaction must be rolled back,
jerojasro@336: Mercurial simply truncates each file back to the size it was before the
jerojasro@336: transaction began.
jerojasro@336: 
jerojasro@336: When Mercurial \emph{reads} metadata, it reads the changelog first,
jerojasro@336: then everything else.  Since a reader will only access parts of the
jerojasro@336: manifest or file metadata that it can see in the changelog, it can
jerojasro@336: never see partially written data.
jerojasro@336: 
jerojasro@336: Some controlling hooks (\hook{pretxncommit} and
jerojasro@336: \hook{pretxnchangegroup}) run when a transaction is almost complete.
jerojasro@336: All of the metadata has been written, but Mercurial can still roll the
jerojasro@336: transaction back and cause the newly-written data to disappear.
jerojasro@336: 
jerojasro@336: If one of these hooks runs for long, it opens a window of time during
jerojasro@336: which a reader can see the metadata for changesets that are not yet
jerojasro@336: permanent, and should not be thought of as ``really there''.  The
jerojasro@336: longer the hook runs, the longer that window is open.
jerojasro@336: 
jerojasro@336: \subsection{The problem illustrated}
jerojasro@336: 
jerojasro@336: In principle, a good use for the \hook{pretxnchangegroup} hook would
jerojasro@336: be to automatically build and test incoming changes before they are
jerojasro@336: accepted into a central repository.  This could let you guarantee that
jerojasro@336: nobody can push changes to this repository that ``break the build''.
jerojasro@336: But if a client can pull changes while they're being tested, the
jerojasro@336: usefulness of the test is zero; an unsuspecting someone can pull
jerojasro@336: untested changes, potentially breaking their build.
jerojasro@336: 
jerojasro@336: The safest technological answer to this challenge is to set up such a
jerojasro@336: ``gatekeeper'' repository as \emph{unidirectional}.  Let it take
jerojasro@336: changes pushed in from the outside, but do not allow anyone to pull
jerojasro@336: changes from it (use the \hook{preoutgoing} hook to lock it down).
jerojasro@336: Configure a \hook{changegroup} hook so that if a build or test
jerojasro@336: succeeds, the hook will push the new changes out to another repository
jerojasro@336: that people \emph{can} pull from.
jerojasro@336: 
jerojasro@336: In practice, putting a centralised bottleneck like this in place is
jerojasro@336: not often a good idea, and transaction visibility has nothing to do
jerojasro@336: with the problem.  As the size of a project---and the time it takes to
jerojasro@336: build and test---grows, you rapidly run into a wall with this ``try
jerojasro@336: before you buy'' approach, where you have more changesets to test than
jerojasro@336: time in which to deal with them.  The inevitable result is frustration
jerojasro@336: on the part of all involved.
jerojasro@336: 
jerojasro@336: An approach that scales better is to get people to build and test
jerojasro@336: before they push, then run automated builds and tests centrally
jerojasro@336: \emph{after} a push, to be sure all is well.  The advantage of this
jerojasro@336: approach is that it does not impose a limit on the rate at which the
jerojasro@336: repository can accept changes.
jerojasro@336: 
jerojasro@336: \section{A short tutorial on using hooks}
jerojasro@336: \label{sec:hook:simple}
jerojasro@336: 
jerojasro@336: It is easy to write a Mercurial hook.  Let's start with a hook that
jerojasro@336: runs when you finish a \hgcmd{commit}, and simply prints the hash of
jerojasro@336: the changeset you just created.  The hook is called \hook{commit}.
jerojasro@336: 
jerojasro@336: \begin{figure}[ht]
jerojasro@336:   \interaction{hook.simple.init}
jerojasro@336:   \caption{A simple hook that runs when a changeset is committed}
jerojasro@336:   \label{ex:hook:init}
jerojasro@336: \end{figure}
jerojasro@336: 
jerojasro@336: All hooks follow the pattern in example~\ref{ex:hook:init}.  You add
jerojasro@336: an entry to the \rcsection{hooks} section of your \hgrc.  On the left
jerojasro@336: is the name of the event to trigger on; on the right is the action to
jerojasro@336: take.  As you can see, you can run an arbitrary shell command in a
jerojasro@336: hook.  Mercurial passes extra information to the hook using
jerojasro@336: environment variables (look for \envar{HG\_NODE} in the example).
jerojasro@336: 
jerojasro@336: \subsection{Performing multiple actions per event}
jerojasro@336: 
jerojasro@336: Quite often, you will want to define more than one hook for a
jerojasro@336: particular kind of event, as shown in example~\ref{ex:hook:ext}.
jerojasro@336: Mercurial lets you do this by adding an \emph{extension} to the end of
jerojasro@336: a hook's name.  You extend a hook's name by giving the name of the
jerojasro@336: hook, followed by a full stop (the ``\texttt{.}'' character), followed
jerojasro@336: by some more text of your choosing.  For example, Mercurial will run
jerojasro@336: both \texttt{commit.foo} and \texttt{commit.bar} when the
jerojasro@336: \texttt{commit} event occurs.
jerojasro@336: 
jerojasro@336: \begin{figure}[ht]
jerojasro@336:   \interaction{hook.simple.ext}
jerojasro@336:   \caption{Defining a second \hook{commit} hook}
jerojasro@336:   \label{ex:hook:ext}
jerojasro@336: \end{figure}
jerojasro@336: 
jerojasro@336: To give a well-defined order of execution when there are multiple
jerojasro@336: hooks defined for an event, Mercurial sorts hooks by extension, and
jerojasro@336: executes the hook commands in this sorted order.  In the above
jerojasro@336: example, it will execute \texttt{commit.bar} before
jerojasro@336: \texttt{commit.foo}, and \texttt{commit} before both.
jerojasro@336: 
jerojasro@336: It is a good idea to use a somewhat descriptive extension when you
jerojasro@336: define a new hook.  This will help you to remember what the hook was
jerojasro@336: for.  If the hook fails, you'll get an error message that contains the
jerojasro@336: hook name and extension, so using a descriptive extension could give
jerojasro@336: you an immediate hint as to why the hook failed (see
jerojasro@336: section~\ref{sec:hook:perm} for an example).
jerojasro@336: 
jerojasro@336: \subsection{Controlling whether an activity can proceed}
jerojasro@336: \label{sec:hook:perm}
jerojasro@336: 
jerojasro@336: In our earlier examples, we used the \hook{commit} hook, which is
jerojasro@336: run after a commit has completed.  This is one of several Mercurial
jerojasro@336: hooks that run after an activity finishes.  Such hooks have no way of
jerojasro@336: influencing the activity itself.
jerojasro@336: 
jerojasro@336: Mercurial defines a number of events that occur before an activity
jerojasro@336: starts; or after it starts, but before it finishes.  Hooks that
jerojasro@336: trigger on these events have the added ability to choose whether the
jerojasro@336: activity can continue, or will abort.  
jerojasro@336: 
jerojasro@336: The \hook{pretxncommit} hook runs after a commit has all but
jerojasro@336: completed.  In other words, the metadata representing the changeset
jerojasro@336: has been written out to disk, but the transaction has not yet been
jerojasro@336: allowed to complete.  The \hook{pretxncommit} hook has the ability to
jerojasro@336: decide whether the transaction can complete, or must be rolled back.
jerojasro@336: 
jerojasro@336: If the \hook{pretxncommit} hook exits with a status code of zero, the
jerojasro@336: transaction is allowed to complete; the commit finishes; and the
jerojasro@336: \hook{commit} hook is run.  If the \hook{pretxncommit} hook exits with
jerojasro@336: a non-zero status code, the transaction is rolled back; the metadata
jerojasro@336: representing the changeset is erased; and the \hook{commit} hook is
jerojasro@336: not run.
jerojasro@336: 
jerojasro@336: \begin{figure}[ht]
jerojasro@336:   \interaction{hook.simple.pretxncommit}
jerojasro@336:   \caption{Using the \hook{pretxncommit} hook to control commits}
jerojasro@336:   \label{ex:hook:pretxncommit}
jerojasro@336: \end{figure}
jerojasro@336: 
jerojasro@336: The hook in example~\ref{ex:hook:pretxncommit} checks that a commit
jerojasro@336: comment contains a bug ID.  If it does, the commit can complete.  If
jerojasro@336: not, the commit is rolled back.
jerojasro@336: 
jerojasro@336: \section{Writing your own hooks}
jerojasro@336: 
jerojasro@336: When you are writing a hook, you might find it useful to run Mercurial
jerojasro@336: either with the \hggopt{-v} option, or the \rcitem{ui}{verbose} config
jerojasro@336: item set to ``true''.  When you do so, Mercurial will print a message
jerojasro@336: before it calls each hook.
jerojasro@336: 
jerojasro@336: \subsection{Choosing how your hook should run}
jerojasro@336: \label{sec:hook:lang}
jerojasro@336: 
jerojasro@336: You can write a hook either as a normal program---typically a shell
jerojasro@336: script---or as a Python function that is executed within the Mercurial
jerojasro@336: process.
jerojasro@336: 
jerojasro@336: Writing a hook as an external program has the advantage that it
jerojasro@336: requires no knowledge of Mercurial's internals.  You can call normal
jerojasro@336: Mercurial commands to get any added information you need.  The
jerojasro@336: trade-off is that external hooks are slower than in-process hooks.
jerojasro@336: 
jerojasro@336: An in-process Python hook has complete access to the Mercurial API,
jerojasro@336: and does not ``shell out'' to another process, so it is inherently
jerojasro@336: faster than an external hook.  It is also easier to obtain much of the
jerojasro@336: information that a hook requires by using the Mercurial API than by
jerojasro@336: running Mercurial commands.
jerojasro@336: 
jerojasro@336: If you are comfortable with Python, or require high performance,
jerojasro@336: writing your hooks in Python may be a good choice.  However, when you
jerojasro@336: have a straightforward hook to write and you don't need to care about
jerojasro@336: performance (probably the majority of hooks), a shell script is
jerojasro@336: perfectly fine.
jerojasro@336: 
jerojasro@336: \subsection{Hook parameters}
jerojasro@336: \label{sec:hook:param}
jerojasro@336: 
jerojasro@336: Mercurial calls each hook with a set of well-defined parameters.  In
jerojasro@336: Python, a parameter is passed as a keyword argument to your hook
jerojasro@336: function.  For an external program, a parameter is passed as an
jerojasro@336: environment variable.
jerojasro@336: 
jerojasro@336: Whether your hook is written in Python or as a shell script, the
jerojasro@336: hook-specific parameter names and values will be the same.  A boolean
jerojasro@336: parameter will be represented as a boolean value in Python, but as the
jerojasro@336: number 1 (for ``true'') or 0 (for ``false'') as an environment
jerojasro@336: variable for an external hook.  If a hook parameter is named
jerojasro@336: \texttt{foo}, the keyword argument for a Python hook will also be
jerojasro@336: named \texttt{foo}, while the environment variable for an external
jerojasro@336: hook will be named \texttt{HG\_FOO}.
jerojasro@336: 
jerojasro@336: \subsection{Hook return values and activity control}
jerojasro@336: 
jerojasro@336: A hook that executes successfully must exit with a status of zero if
jerojasro@336: external, or return boolean ``false'' if in-process.  Failure is
jerojasro@336: indicated with a non-zero exit status from an external hook, or an
jerojasro@336: in-process hook returning boolean ``true''.  If an in-process hook
jerojasro@336: raises an exception, the hook is considered to have failed.
jerojasro@336: 
jerojasro@336: For a hook that controls whether an activity can proceed, zero/false
jerojasro@336: means ``allow'', while non-zero/true/exception means ``deny''.
jerojasro@336: 
jerojasro@336: \subsection{Writing an external hook}
jerojasro@336: 
jerojasro@336: When you define an external hook in your \hgrc\ and the hook is run,
jerojasro@336: its value is passed to your shell, which interprets it.  This means
jerojasro@336: that you can use normal shell constructs in the body of the hook.
jerojasro@336: 
jerojasro@336: An executable hook is always run with its current directory set to a
jerojasro@336: repository's root directory.
jerojasro@336: 
jerojasro@336: Each hook parameter is passed in as an environment variable; the name
jerojasro@336: is upper-cased, and prefixed with the string ``\texttt{HG\_}''.
jerojasro@336: 
jerojasro@336: With the exception of hook parameters, Mercurial does not set or
jerojasro@336: modify any environment variables when running a hook.  This is useful
jerojasro@336: to remember if you are writing a site-wide hook that may be run by a
jerojasro@336: number of different users with differing environment variables set.
jerojasro@336: In multi-user situations, you should not rely on environment variables
jerojasro@336: being set to the values you have in your environment when testing the
jerojasro@336: hook.
jerojasro@336: 
jerojasro@336: \subsection{Telling Mercurial to use an in-process hook}
jerojasro@336: 
jerojasro@336: The \hgrc\ syntax for defining an in-process hook is slightly
jerojasro@336: different than for an executable hook.  The value of the hook must
jerojasro@336: start with the text ``\texttt{python:}'', and continue with the
jerojasro@336: fully-qualified name of a callable object to use as the hook's value.
jerojasro@336: 
jerojasro@336: The module in which a hook lives is automatically imported when a hook
jerojasro@336: is run.  So long as you have the module name and \envar{PYTHONPATH}
jerojasro@336: right, it should ``just work''.
jerojasro@336: 
jerojasro@336: The following \hgrc\ example snippet illustrates the syntax and
jerojasro@336: meaning of the notions we just described.
jerojasro@336: \begin{codesample2}
jerojasro@336:   [hooks]
jerojasro@336:   commit.example = python:mymodule.submodule.myhook
jerojasro@336: \end{codesample2}
jerojasro@336: When Mercurial runs the \texttt{commit.example} hook, it imports
jerojasro@336: \texttt{mymodule.submodule}, looks for the callable object named
jerojasro@336: \texttt{myhook}, and calls it.
jerojasro@336: 
jerojasro@336: \subsection{Writing an in-process hook}
jerojasro@336: 
jerojasro@336: The simplest in-process hook does nothing, but illustrates the basic
jerojasro@336: shape of the hook API:
jerojasro@336: \begin{codesample2}
jerojasro@336:   def myhook(ui, repo, **kwargs):
jerojasro@336:       pass
jerojasro@336: \end{codesample2}
jerojasro@336: The first argument to a Python hook is always a
jerojasro@336: \pymodclass{mercurial.ui}{ui} object.  The second is a repository object;
jerojasro@336: at the moment, it is always an instance of
jerojasro@336: \pymodclass{mercurial.localrepo}{localrepository}.  Following these two
jerojasro@336: arguments are other keyword arguments.  Which ones are passed in
jerojasro@336: depends on the hook being called, but a hook can ignore arguments it
jerojasro@336: doesn't care about by dropping them into a keyword argument dict, as
jerojasro@336: with \texttt{**kwargs} above.
jerojasro@336: 
jerojasro@336: \section{Some hook examples}
jerojasro@336: 
jerojasro@336: \subsection{Writing meaningful commit messages}
jerojasro@336: 
jerojasro@336: It's hard to imagine a useful commit message being very short.  The
jerojasro@336: simple \hook{pretxncommit} hook of figure~\ref{ex:hook:msglen.go}
jerojasro@336: will prevent you from committing a changeset with a message that is
jerojasro@336: less than ten bytes long.
jerojasro@336: 
jerojasro@336: \begin{figure}[ht]
jerojasro@336:   \interaction{hook.msglen.go}
jerojasro@336:   \caption{A hook that forbids overly short commit messages}
jerojasro@336:   \label{ex:hook:msglen.go}
jerojasro@336: \end{figure}
jerojasro@336: 
jerojasro@336: \subsection{Checking for trailing whitespace}
jerojasro@336: 
jerojasro@336: An interesting use of a commit-related hook is to help you to write
jerojasro@336: cleaner code.  A simple example of ``cleaner code'' is the dictum that
jerojasro@336: a change should not add any new lines of text that contain ``trailing
jerojasro@336: whitespace''.  Trailing whitespace is a series of space and tab
jerojasro@336: characters at the end of a line of text.  In most cases, trailing
jerojasro@336: whitespace is unnecessary, invisible noise, but it is occasionally
jerojasro@336: problematic, and people often prefer to get rid of it.
jerojasro@336: 
jerojasro@336: You can use either the \hook{precommit} or \hook{pretxncommit} hook to
jerojasro@336: tell whether you have a trailing whitespace problem.  If you use the
jerojasro@336: \hook{precommit} hook, the hook will not know which files you are
jerojasro@336: committing, so it will have to check every modified file in the
jerojasro@336: repository for trailing white space.  If you want to commit a change
jerojasro@336: to just the file \filename{foo}, but the file \filename{bar} contains
jerojasro@336: trailing whitespace, doing a check in the \hook{precommit} hook will
jerojasro@336: prevent you from committing \filename{foo} due to the problem with
jerojasro@336: \filename{bar}.  This doesn't seem right.
jerojasro@336: 
jerojasro@336: Should you choose the \hook{pretxncommit} hook, the check won't occur
jerojasro@336: until just before the transaction for the commit completes.  This will
jerojasro@336: allow you to check for problems only the exact files that are being
jerojasro@336: committed.  However, if you entered the commit message interactively
jerojasro@336: and the hook fails, the transaction will roll back; you'll have to
jerojasro@336: re-enter the commit message after you fix the trailing whitespace and
jerojasro@336: run \hgcmd{commit} again.
jerojasro@336: 
jerojasro@336: \begin{figure}[ht]
jerojasro@336:   \interaction{hook.ws.simple}
jerojasro@336:   \caption{A simple hook that checks for trailing whitespace}
jerojasro@336:   \label{ex:hook:ws.simple}
jerojasro@336: \end{figure}
jerojasro@336: 
jerojasro@336: Figure~\ref{ex:hook:ws.simple} introduces a simple \hook{pretxncommit}
jerojasro@336: hook that checks for trailing whitespace.  This hook is short, but not
jerojasro@336: very helpful.  It exits with an error status if a change adds a line
jerojasro@336: with trailing whitespace to any file, but does not print any
jerojasro@336: information that might help us to identify the offending file or
jerojasro@336: line.  It also has the nice property of not paying attention to
jerojasro@336: unmodified lines; only lines that introduce new trailing whitespace
jerojasro@336: cause problems.
jerojasro@336: 
jerojasro@336: \begin{figure}[ht]
jerojasro@336:   \interaction{hook.ws.better}
jerojasro@336:   \caption{A better trailing whitespace hook}
jerojasro@336:   \label{ex:hook:ws.better}
jerojasro@336: \end{figure}
jerojasro@336: 
jerojasro@336: The example of figure~\ref{ex:hook:ws.better} is much more complex,
jerojasro@336: but also more useful.  It parses a unified diff to see if any lines
jerojasro@336: add trailing whitespace, and prints the name of the file and the line
jerojasro@336: number of each such occurrence.  Even better, if the change adds
jerojasro@336: trailing whitespace, this hook saves the commit comment and prints the
jerojasro@336: name of the save file before exiting and telling Mercurial to roll the
jerojasro@336: transaction back, so you can use
jerojasro@336: \hgcmdargs{commit}{\hgopt{commit}{-l}~\emph{filename}} to reuse the
jerojasro@336: saved commit message once you've corrected the problem.
jerojasro@336: 
jerojasro@336: As a final aside, note in figure~\ref{ex:hook:ws.better} the use of
jerojasro@336: \command{perl}'s in-place editing feature to get rid of trailing
jerojasro@336: whitespace from a file.  This is concise and useful enough that I will
jerojasro@336: reproduce it here.
jerojasro@336: \begin{codesample2}
jerojasro@336:   perl -pi -e 's,\\s+\$,,' filename
jerojasro@336: \end{codesample2}
jerojasro@336: 
jerojasro@336: \section{Bundled hooks}
jerojasro@336: 
jerojasro@336: Mercurial ships with several bundled hooks.  You can find them in the
jerojasro@336: \dirname{hgext} directory of a Mercurial source tree.  If you are
jerojasro@336: using a Mercurial binary package, the hooks will be located in the
jerojasro@336: \dirname{hgext} directory of wherever your package installer put
jerojasro@336: Mercurial.
jerojasro@336: 
jerojasro@336: \subsection{\hgext{acl}---access control for parts of a repository}
jerojasro@336: 
jerojasro@336: The \hgext{acl} extension lets you control which remote users are
jerojasro@336: allowed to push changesets to a networked server.  You can protect any
jerojasro@336: portion of a repository (including the entire repo), so that a
jerojasro@336: specific remote user can push changes that do not affect the protected
jerojasro@336: portion.
jerojasro@336: 
jerojasro@336: This extension implements access control based on the identity of the
jerojasro@336: user performing a push, \emph{not} on who committed the changesets
jerojasro@336: they're pushing.  It makes sense to use this hook only if you have a
jerojasro@336: locked-down server environment that authenticates remote users, and
jerojasro@336: you want to be sure that only specific users are allowed to push
jerojasro@336: changes to that server.
jerojasro@336: 
jerojasro@336: \subsubsection{Configuring the \hook{acl} hook}
jerojasro@336: 
jerojasro@336: In order to manage incoming changesets, the \hgext{acl} hook must be
jerojasro@336: used as a \hook{pretxnchangegroup} hook.  This lets it see which files
jerojasro@336: are modified by each incoming changeset, and roll back a group of
jerojasro@336: changesets if they modify ``forbidden'' files.  Example:
jerojasro@336: \begin{codesample2}
jerojasro@336:   [hooks]
jerojasro@336:   pretxnchangegroup.acl = python:hgext.acl.hook
jerojasro@336: \end{codesample2}
jerojasro@336: 
jerojasro@336: The \hgext{acl} extension is configured using three sections.  
jerojasro@336: 
jerojasro@336: The \rcsection{acl} section has only one entry, \rcitem{acl}{sources},
jerojasro@336: which lists the sources of incoming changesets that the hook should
jerojasro@336: pay attention to.  You don't normally need to configure this section.
jerojasro@336: \begin{itemize}
jerojasro@336: \item[\rcitem{acl}{serve}] Control incoming changesets that are arriving
jerojasro@336:   from a remote repository over http or ssh.  This is the default
jerojasro@336:   value of \rcitem{acl}{sources}, and usually the only setting you'll
jerojasro@336:   need for this configuration item.
jerojasro@336: \item[\rcitem{acl}{pull}] Control incoming changesets that are
jerojasro@336:   arriving via a pull from a local repository.
jerojasro@336: \item[\rcitem{acl}{push}] Control incoming changesets that are
jerojasro@336:   arriving via a push from a local repository.
jerojasro@336: \item[\rcitem{acl}{bundle}] Control incoming changesets that are
jerojasro@336:   arriving from another repository via a bundle.
jerojasro@336: \end{itemize}
jerojasro@336: 
jerojasro@336: The \rcsection{acl.allow} section controls the users that are allowed to
jerojasro@336: add changesets to the repository.  If this section is not present, all
jerojasro@336: users that are not explicitly denied are allowed.  If this section is
jerojasro@336: present, all users that are not explicitly allowed are denied (so an
jerojasro@336: empty section means that all users are denied).
jerojasro@336: 
jerojasro@336: The \rcsection{acl.deny} section determines which users are denied
jerojasro@336: from adding changesets to the repository.  If this section is not
jerojasro@336: present or is empty, no users are denied.
jerojasro@336: 
jerojasro@336: The syntaxes for the \rcsection{acl.allow} and \rcsection{acl.deny}
jerojasro@336: sections are identical.  On the left of each entry is a glob pattern
jerojasro@336: that matches files or directories, relative to the root of the
jerojasro@336: repository; on the right, a user name.
jerojasro@336: 
jerojasro@336: In the following example, the user \texttt{docwriter} can only push
jerojasro@336: changes to the \dirname{docs} subtree of the repository, while
jerojasro@336: \texttt{intern} can push changes to any file or directory except
jerojasro@336: \dirname{source/sensitive}.
jerojasro@336: \begin{codesample2}
jerojasro@336:   [acl.allow]
jerojasro@336:   docs/** = docwriter
jerojasro@336: 
jerojasro@336:   [acl.deny]
jerojasro@336:   source/sensitive/** = intern
jerojasro@336: \end{codesample2}
jerojasro@336: 
jerojasro@336: \subsubsection{Testing and troubleshooting}
jerojasro@336: 
jerojasro@336: If you want to test the \hgext{acl} hook, run it with Mercurial's
jerojasro@336: debugging output enabled.  Since you'll probably be running it on a
jerojasro@336: server where it's not convenient (or sometimes possible) to pass in
jerojasro@336: the \hggopt{--debug} option, don't forget that you can enable
jerojasro@336: debugging output in your \hgrc:
jerojasro@336: \begin{codesample2}
jerojasro@336:   [ui]
jerojasro@336:   debug = true
jerojasro@336: \end{codesample2}
jerojasro@336: With this enabled, the \hgext{acl} hook will print enough information
jerojasro@336: to let you figure out why it is allowing or forbidding pushes from
jerojasro@336: specific users.
jerojasro@336: 
jerojasro@336: \subsection{\hgext{bugzilla}---integration with Bugzilla}
jerojasro@336: 
jerojasro@336: The \hgext{bugzilla} extension adds a comment to a Bugzilla bug
jerojasro@336: whenever it finds a reference to that bug ID in a commit comment.  You
jerojasro@336: can install this hook on a shared server, so that any time a remote
jerojasro@336: user pushes changes to this server, the hook gets run.  
jerojasro@336: 
jerojasro@336: It adds a comment to the bug that looks like this (you can configure
jerojasro@336: the contents of the comment---see below):
jerojasro@336: \begin{codesample2}
jerojasro@336:   Changeset aad8b264143a, made by Joe User <joe.user@domain.com> in
jerojasro@336:   the frobnitz repository, refers to this bug.
jerojasro@336: 
jerojasro@336:   For complete details, see
jerojasro@336:   http://hg.domain.com/frobnitz?cmd=changeset;node=aad8b264143a
jerojasro@336: 
jerojasro@336:   Changeset description:
jerojasro@336:         Fix bug 10483 by guarding against some NULL pointers
jerojasro@336: \end{codesample2}
jerojasro@336: The value of this hook is that it automates the process of updating a
jerojasro@336: bug any time a changeset refers to it.  If you configure the hook
jerojasro@336: properly, it makes it easy for people to browse straight from a
jerojasro@336: Bugzilla bug to a changeset that refers to that bug.
jerojasro@336: 
jerojasro@336: You can use the code in this hook as a starting point for some more
jerojasro@336: exotic Bugzilla integration recipes.  Here are a few possibilities:
jerojasro@336: \begin{itemize}
jerojasro@336: \item Require that every changeset pushed to the server have a valid
jerojasro@336:   bug~ID in its commit comment.  In this case, you'd want to configure
jerojasro@336:   the hook as a \hook{pretxncommit} hook.  This would allow the hook
jerojasro@336:   to reject changes that didn't contain bug IDs.
jerojasro@336: \item Allow incoming changesets to automatically modify the
jerojasro@336:   \emph{state} of a bug, as well as simply adding a comment.  For
jerojasro@336:   example, the hook could recognise the string ``fixed bug 31337'' as
jerojasro@336:   indicating that it should update the state of bug 31337 to
jerojasro@336:   ``requires testing''.
jerojasro@336: \end{itemize}
jerojasro@336: 
jerojasro@336: \subsubsection{Configuring the \hook{bugzilla} hook}
jerojasro@336: \label{sec:hook:bugzilla:config}
jerojasro@336: 
jerojasro@336: You should configure this hook in your server's \hgrc\ as an
jerojasro@336: \hook{incoming} hook, for example as follows:
jerojasro@336: \begin{codesample2}
jerojasro@336:   [hooks]
jerojasro@336:   incoming.bugzilla = python:hgext.bugzilla.hook
jerojasro@336: \end{codesample2}
jerojasro@336: 
jerojasro@336: Because of the specialised nature of this hook, and because Bugzilla
jerojasro@336: was not written with this kind of integration in mind, configuring
jerojasro@336: this hook is a somewhat involved process.
jerojasro@336: 
jerojasro@336: Before you begin, you must install the MySQL bindings for Python on
jerojasro@336: the host(s) where you'll be running the hook.  If this is not
jerojasro@336: available as a binary package for your system, you can download it
jerojasro@336: from~\cite{web:mysql-python}.
jerojasro@336: 
jerojasro@336: Configuration information for this hook lives in the
jerojasro@336: \rcsection{bugzilla} section of your \hgrc.
jerojasro@336: \begin{itemize}
jerojasro@336: \item[\rcitem{bugzilla}{version}] The version of Bugzilla installed on
jerojasro@336:   the server.  The database schema that Bugzilla uses changes
jerojasro@336:   occasionally, so this hook has to know exactly which schema to use.
jerojasro@336:   At the moment, the only version supported is \texttt{2.16}.
jerojasro@336: \item[\rcitem{bugzilla}{host}] The hostname of the MySQL server that
jerojasro@336:   stores your Bugzilla data.  The database must be configured to allow
jerojasro@336:   connections from whatever host you are running the \hook{bugzilla}
jerojasro@336:   hook on.
jerojasro@336: \item[\rcitem{bugzilla}{user}] The username with which to connect to
jerojasro@336:   the MySQL server.  The database must be configured to allow this
jerojasro@336:   user to connect from whatever host you are running the
jerojasro@336:   \hook{bugzilla} hook on.  This user must be able to access and
jerojasro@336:   modify Bugzilla tables.  The default value of this item is
jerojasro@336:   \texttt{bugs}, which is the standard name of the Bugzilla user in a
jerojasro@336:   MySQL database.
jerojasro@336: \item[\rcitem{bugzilla}{password}] The MySQL password for the user you
jerojasro@336:   configured above.  This is stored as plain text, so you should make
jerojasro@336:   sure that unauthorised users cannot read the \hgrc\ file where you
jerojasro@336:   store this information.
jerojasro@336: \item[\rcitem{bugzilla}{db}] The name of the Bugzilla database on the
jerojasro@336:   MySQL server.  The default value of this item is \texttt{bugs},
jerojasro@336:   which is the standard name of the MySQL database where Bugzilla
jerojasro@336:   stores its data.
jerojasro@336: \item[\rcitem{bugzilla}{notify}] If you want Bugzilla to send out a
jerojasro@336:   notification email to subscribers after this hook has added a
jerojasro@336:   comment to a bug, you will need this hook to run a command whenever
jerojasro@336:   it updates the database.  The command to run depends on where you
jerojasro@336:   have installed Bugzilla, but it will typically look something like
jerojasro@336:   this, if you have Bugzilla installed in
jerojasro@336:   \dirname{/var/www/html/bugzilla}:
jerojasro@336:   \begin{codesample4}
jerojasro@336:     cd /var/www/html/bugzilla && ./processmail %s nobody@nowhere.com
jerojasro@336:   \end{codesample4}
jerojasro@336:   The Bugzilla \texttt{processmail} program expects to be given a
jerojasro@336:   bug~ID (the hook replaces ``\texttt{\%s}'' with the bug~ID) and an
jerojasro@336:   email address.  It also expects to be able to write to some files in
jerojasro@336:   the directory that it runs in.  If Bugzilla and this hook are not
jerojasro@336:   installed on the same machine, you will need to find a way to run
jerojasro@336:   \texttt{processmail} on the server where Bugzilla is installed.
jerojasro@336: \end{itemize}
jerojasro@336: 
jerojasro@336: \subsubsection{Mapping committer names to Bugzilla user names}
jerojasro@336: 
jerojasro@336: By default, the \hgext{bugzilla} hook tries to use the email address
jerojasro@336: of a changeset's committer as the Bugzilla user name with which to
jerojasro@336: update a bug.  If this does not suit your needs, you can map committer
jerojasro@336: email addresses to Bugzilla user names using a \rcsection{usermap}
jerojasro@336: section.
jerojasro@336: 
jerojasro@336: Each item in the \rcsection{usermap} section contains an email address
jerojasro@336: on the left, and a Bugzilla user name on the right.
jerojasro@336: \begin{codesample2}
jerojasro@336:   [usermap]
jerojasro@336:   jane.user@example.com = jane
jerojasro@336: \end{codesample2}
jerojasro@336: You can either keep the \rcsection{usermap} data in a normal \hgrc, or
jerojasro@336: tell the \hgext{bugzilla} hook to read the information from an
jerojasro@336: external \filename{usermap} file.  In the latter case, you can store
jerojasro@336: \filename{usermap} data by itself in (for example) a user-modifiable
jerojasro@336: repository.  This makes it possible to let your users maintain their
jerojasro@336: own \rcitem{bugzilla}{usermap} entries.  The main \hgrc\ file might
jerojasro@336: look like this:
jerojasro@336: \begin{codesample2}
jerojasro@336:   # regular hgrc file refers to external usermap file
jerojasro@336:   [bugzilla]
jerojasro@336:   usermap = /home/hg/repos/userdata/bugzilla-usermap.conf
jerojasro@336: \end{codesample2}
jerojasro@336: While the \filename{usermap} file that it refers to might look like
jerojasro@336: this:
jerojasro@336: \begin{codesample2}
jerojasro@336:   # bugzilla-usermap.conf - inside a hg repository
jerojasro@336:   [usermap]
jerojasro@336:   stephanie@example.com = steph
jerojasro@336: \end{codesample2}
jerojasro@336: 
jerojasro@336: \subsubsection{Configuring the text that gets added to a bug}
jerojasro@336: 
jerojasro@336: You can configure the text that this hook adds as a comment; you
jerojasro@336: specify it in the form of a Mercurial template.  Several \hgrc\
jerojasro@336: entries (still in the \rcsection{bugzilla} section) control this
jerojasro@336: behaviour.
jerojasro@336: \begin{itemize}
jerojasro@336: \item[\texttt{strip}] The number of leading path elements to strip
jerojasro@336:   from a repository's path name to construct a partial path for a URL.
jerojasro@336:   For example, if the repositories on your server live under
jerojasro@336:   \dirname{/home/hg/repos}, and you have a repository whose path is
jerojasro@336:   \dirname{/home/hg/repos/app/tests}, then setting \texttt{strip} to
jerojasro@336:   \texttt{4} will give a partial path of \dirname{app/tests}.  The
jerojasro@336:   hook will make this partial path available when expanding a
jerojasro@336:   template, as \texttt{webroot}.
jerojasro@336: \item[\texttt{template}] The text of the template to use.  In addition
jerojasro@336:   to the usual changeset-related variables, this template can use
jerojasro@336:   \texttt{hgweb} (the value of the \texttt{hgweb} configuration item
jerojasro@336:   above) and \texttt{webroot} (the path constructed using
jerojasro@336:   \texttt{strip} above).
jerojasro@336: \end{itemize}
jerojasro@336: 
jerojasro@336: In addition, you can add a \rcitem{web}{baseurl} item to the
jerojasro@336: \rcsection{web} section of your \hgrc.  The \hgext{bugzilla} hook will
jerojasro@336: make this available when expanding a template, as the base string to
jerojasro@336: use when constructing a URL that will let users browse from a Bugzilla
jerojasro@336: comment to view a changeset.  Example:
jerojasro@336: \begin{codesample2}
jerojasro@336:   [web]
jerojasro@336:   baseurl = http://hg.domain.com/
jerojasro@336: \end{codesample2}
jerojasro@336: 
jerojasro@336: Here is an example set of \hgext{bugzilla} hook config information.
jerojasro@336: \begin{codesample2}
jerojasro@336:   [bugzilla]
jerojasro@336:   host = bugzilla.example.com
jerojasro@336:   password = mypassword
jerojasro@336:   version = 2.16
jerojasro@336:   # server-side repos live in /home/hg/repos, so strip 4 leading
jerojasro@336:   # separators
jerojasro@336:   strip = 4
jerojasro@336:   hgweb = http://hg.example.com/
jerojasro@336:   usermap = /home/hg/repos/notify/bugzilla.conf
jerojasro@336:   template = Changeset \{node|short\}, made by \{author\} in the \{webroot\}
jerojasro@336:     repo, refers to this bug.\\nFor complete details, see 
jerojasro@336:     \{hgweb\}\{webroot\}?cmd=changeset;node=\{node|short\}\\nChangeset
jerojasro@336:     description:\\n\\t\{desc|tabindent\}
jerojasro@336: \end{codesample2}
jerojasro@336: 
jerojasro@336: \subsubsection{Testing and troubleshooting}
jerojasro@336: 
jerojasro@336: The most common problems with configuring the \hgext{bugzilla} hook
jerojasro@336: relate to running Bugzilla's \filename{processmail} script and mapping
jerojasro@336: committer names to user names.
jerojasro@336: 
jerojasro@336: Recall from section~\ref{sec:hook:bugzilla:config} above that the user
jerojasro@336: that runs the Mercurial process on the server is also the one that
jerojasro@336: will run the \filename{processmail} script.  The
jerojasro@336: \filename{processmail} script sometimes causes Bugzilla to write to
jerojasro@336: files in its configuration directory, and Bugzilla's configuration
jerojasro@336: files are usually owned by the user that your web server runs under.
jerojasro@336: 
jerojasro@336: You can cause \filename{processmail} to be run with the suitable
jerojasro@336: user's identity using the \command{sudo} command.  Here is an example
jerojasro@336: entry for a \filename{sudoers} file.
jerojasro@336: \begin{codesample2}
jerojasro@336:   hg_user = (httpd_user) NOPASSWD: /var/www/html/bugzilla/processmail-wrapper %s
jerojasro@336: \end{codesample2}
jerojasro@336: This allows the \texttt{hg\_user} user to run a
jerojasro@336: \filename{processmail-wrapper} program under the identity of
jerojasro@336: \texttt{httpd\_user}.
jerojasro@336: 
jerojasro@336: This indirection through a wrapper script is necessary, because
jerojasro@336: \filename{processmail} expects to be run with its current directory
jerojasro@336: set to wherever you installed Bugzilla; you can't specify that kind of
jerojasro@336: constraint in a \filename{sudoers} file.  The contents of the wrapper
jerojasro@336: script are simple:
jerojasro@336: \begin{codesample2}
jerojasro@336:   #!/bin/sh
jerojasro@336:   cd `dirname $0` && ./processmail "$1" nobody@example.com
jerojasro@336: \end{codesample2}
jerojasro@336: It doesn't seem to matter what email address you pass to
jerojasro@336: \filename{processmail}.
jerojasro@336: 
jerojasro@336: If your \rcsection{usermap} is not set up correctly, users will see an
jerojasro@336: error message from the \hgext{bugzilla} hook when they push changes
jerojasro@336: to the server.  The error message will look like this:
jerojasro@336: \begin{codesample2}
jerojasro@336:   cannot find bugzilla user id for john.q.public@example.com
jerojasro@336: \end{codesample2}
jerojasro@336: What this means is that the committer's address,
jerojasro@336: \texttt{john.q.public@example.com}, is not a valid Bugzilla user name,
jerojasro@336: nor does it have an entry in your \rcsection{usermap} that maps it to
jerojasro@336: a valid Bugzilla user name.
jerojasro@336: 
jerojasro@336: \subsection{\hgext{notify}---send email notifications}
jerojasro@336: 
jerojasro@336: Although Mercurial's built-in web server provides RSS feeds of changes
jerojasro@336: in every repository, many people prefer to receive change
jerojasro@336: notifications via email.  The \hgext{notify} hook lets you send out
jerojasro@336: notifications to a set of email addresses whenever changesets arrive
jerojasro@336: that those subscribers are interested in.
jerojasro@336: 
jerojasro@336: As with the \hgext{bugzilla} hook, the \hgext{notify} hook is
jerojasro@336: template-driven, so you can customise the contents of the notification
jerojasro@336: messages that it sends.
jerojasro@336: 
jerojasro@336: By default, the \hgext{notify} hook includes a diff of every changeset
jerojasro@336: that it sends out; you can limit the size of the diff, or turn this
jerojasro@336: feature off entirely.  It is useful for letting subscribers review
jerojasro@336: changes immediately, rather than clicking to follow a URL.
jerojasro@336: 
jerojasro@336: \subsubsection{Configuring the \hgext{notify} hook}
jerojasro@336: 
jerojasro@336: You can set up the \hgext{notify} hook to send one email message per
jerojasro@336: incoming changeset, or one per incoming group of changesets (all those
jerojasro@336: that arrived in a single pull or push).
jerojasro@336: \begin{codesample2}
jerojasro@336:   [hooks]
jerojasro@336:   # send one email per group of changes
jerojasro@336:   changegroup.notify = python:hgext.notify.hook
jerojasro@336:   # send one email per change
jerojasro@336:   incoming.notify = python:hgext.notify.hook
jerojasro@336: \end{codesample2}
jerojasro@336: 
jerojasro@336: Configuration information for this hook lives in the
jerojasro@336: \rcsection{notify} section of a \hgrc\ file.
jerojasro@336: \begin{itemize}
jerojasro@336: \item[\rcitem{notify}{test}] By default, this hook does not send out
jerojasro@336:   email at all; instead, it prints the message that it \emph{would}
jerojasro@336:   send.  Set this item to \texttt{false} to allow email to be sent.
jerojasro@336:   The reason that sending of email is turned off by default is that it
jerojasro@336:   takes several tries to configure this extension exactly as you would
jerojasro@336:   like, and it would be bad form to spam subscribers with a number of
jerojasro@336:   ``broken'' notifications while you debug your configuration.
jerojasro@336: \item[\rcitem{notify}{config}] The path to a configuration file that
jerojasro@336:   contains subscription information.  This is kept separate from the
jerojasro@336:   main \hgrc\ so that you can maintain it in a repository of its own.
jerojasro@336:   People can then clone that repository, update their subscriptions,
jerojasro@336:   and push the changes back to your server.
jerojasro@336: \item[\rcitem{notify}{strip}] The number of leading path separator
jerojasro@336:   characters to strip from a repository's path, when deciding whether
jerojasro@336:   a repository has subscribers.  For example, if the repositories on
jerojasro@336:   your server live in \dirname{/home/hg/repos}, and \hgext{notify} is
jerojasro@336:   considering a repository named \dirname{/home/hg/repos/shared/test},
jerojasro@336:   setting \rcitem{notify}{strip} to \texttt{4} will cause
jerojasro@336:   \hgext{notify} to trim the path it considers down to
jerojasro@336:   \dirname{shared/test}, and it will match subscribers against that.
jerojasro@336: \item[\rcitem{notify}{template}] The template text to use when sending
jerojasro@336:   messages.  This specifies both the contents of the message header
jerojasro@336:   and its body.
jerojasro@336: \item[\rcitem{notify}{maxdiff}] The maximum number of lines of diff
jerojasro@336:   data to append to the end of a message.  If a diff is longer than
jerojasro@336:   this, it is truncated.  By default, this is set to 300.  Set this to
jerojasro@336:   \texttt{0} to omit diffs from notification emails.
jerojasro@336: \item[\rcitem{notify}{sources}] A list of sources of changesets to
jerojasro@336:   consider.  This lets you limit \hgext{notify} to only sending out
jerojasro@336:   email about changes that remote users pushed into this repository
jerojasro@336:   via a server, for example.  See section~\ref{sec:hook:sources} for
jerojasro@336:   the sources you can specify here.
jerojasro@336: \end{itemize}
jerojasro@336: 
jerojasro@336: If you set the \rcitem{web}{baseurl} item in the \rcsection{web}
jerojasro@336: section, you can use it in a template; it will be available as
jerojasro@336: \texttt{webroot}.
jerojasro@336: 
jerojasro@336: Here is an example set of \hgext{notify} configuration information.
jerojasro@336: \begin{codesample2}
jerojasro@336:   [notify]
jerojasro@336:   # really send email
jerojasro@336:   test = false
jerojasro@336:   # subscriber data lives in the notify repo
jerojasro@336:   config = /home/hg/repos/notify/notify.conf
jerojasro@336:   # repos live in /home/hg/repos on server, so strip 4 "/" chars
jerojasro@336:   strip = 4
jerojasro@336:   template = X-Hg-Repo: \{webroot\}
jerojasro@336:     Subject: \{webroot\}: \{desc|firstline|strip\}
jerojasro@336:     From: \{author\}
jerojasro@336: 
jerojasro@336:     changeset \{node|short\} in \{root\}
jerojasro@336:     details: \{baseurl\}\{webroot\}?cmd=changeset;node=\{node|short\}
jerojasro@336:     description:
jerojasro@336:       \{desc|tabindent|strip\}
jerojasro@336: 
jerojasro@336:   [web]
jerojasro@336:   baseurl = http://hg.example.com/
jerojasro@336: \end{codesample2}
jerojasro@336: 
jerojasro@336: This will produce a message that looks like the following:
jerojasro@336: \begin{codesample2}
jerojasro@336:   X-Hg-Repo: tests/slave
jerojasro@336:   Subject: tests/slave: Handle error case when slave has no buffers
jerojasro@336:   Date: Wed,  2 Aug 2006 15:25:46 -0700 (PDT)
jerojasro@336: 
jerojasro@336:   changeset 3cba9bfe74b5 in /home/hg/repos/tests/slave
jerojasro@336:   details: http://hg.example.com/tests/slave?cmd=changeset;node=3cba9bfe74b5
jerojasro@336:   description:
jerojasro@336:           Handle error case when slave has no buffers
jerojasro@336:   diffs (54 lines):
jerojasro@336: 
jerojasro@336:   diff -r 9d95df7cf2ad -r 3cba9bfe74b5 include/tests.h
jerojasro@336:   --- a/include/tests.h      Wed Aug 02 15:19:52 2006 -0700
jerojasro@336:   +++ b/include/tests.h      Wed Aug 02 15:25:26 2006 -0700
jerojasro@336:   @@ -212,6 +212,15 @@ static __inline__ void test_headers(void *h)
jerojasro@336:   [...snip...]
jerojasro@336: \end{codesample2}
jerojasro@336: 
jerojasro@336: \subsubsection{Testing and troubleshooting}
jerojasro@336: 
jerojasro@336: Do not forget that by default, the \hgext{notify} extension \emph{will
jerojasro@336:   not send any mail} until you explicitly configure it to do so, by
jerojasro@336: setting \rcitem{notify}{test} to \texttt{false}.  Until you do that,
jerojasro@336: it simply prints the message it \emph{would} send.
jerojasro@336: 
jerojasro@336: \section{Information for writers of hooks}
jerojasro@336: \label{sec:hook:ref}
jerojasro@336: 
jerojasro@336: \subsection{In-process hook execution}
jerojasro@336: 
jerojasro@336: An in-process hook is called with arguments of the following form:
jerojasro@336: \begin{codesample2}
jerojasro@336:   def myhook(ui, repo, **kwargs):
jerojasro@336:       pass
jerojasro@336: \end{codesample2}
jerojasro@336: The \texttt{ui} parameter is a \pymodclass{mercurial.ui}{ui} object.
jerojasro@336: The \texttt{repo} parameter is a
jerojasro@336: \pymodclass{mercurial.localrepo}{localrepository} object.  The
jerojasro@336: names and values of the \texttt{**kwargs} parameters depend on the
jerojasro@336: hook being invoked, with the following common features:
jerojasro@336: \begin{itemize}
jerojasro@336: \item If a parameter is named \texttt{node} or
jerojasro@336:   \texttt{parent\emph{N}}, it will contain a hexadecimal changeset ID.
jerojasro@336:   The empty string is used to represent ``null changeset ID'' instead
jerojasro@336:   of a string of zeroes.
jerojasro@336: \item If a parameter is named \texttt{url}, it will contain the URL of
jerojasro@336:   a remote repository, if that can be determined.
jerojasro@336: \item Boolean-valued parameters are represented as Python
jerojasro@336:   \texttt{bool} objects.
jerojasro@336: \end{itemize}
jerojasro@336: 
jerojasro@336: An in-process hook is called without a change to the process's working
jerojasro@336: directory (unlike external hooks, which are run in the root of the
jerojasro@336: repository).  It must not change the process's working directory, or
jerojasro@336: it will cause any calls it makes into the Mercurial API to fail.
jerojasro@336: 
jerojasro@336: If a hook returns a boolean ``false'' value, it is considered to have
jerojasro@336: succeeded.  If it returns a boolean ``true'' value or raises an
jerojasro@336: exception, it is considered to have failed.  A useful way to think of
jerojasro@336: the calling convention is ``tell me if you fail''.
jerojasro@336: 
jerojasro@336: Note that changeset IDs are passed into Python hooks as hexadecimal
jerojasro@336: strings, not the binary hashes that Mercurial's APIs normally use.  To
jerojasro@336: convert a hash from hex to binary, use the
jerojasro@336: \pymodfunc{mercurial.node}{bin} function.
jerojasro@336: 
jerojasro@336: \subsection{External hook execution}
jerojasro@336: 
jerojasro@336: An external hook is passed to the shell of the user running Mercurial.
jerojasro@336: Features of that shell, such as variable substitution and command
jerojasro@336: redirection, are available.  The hook is run in the root directory of
jerojasro@336: the repository (unlike in-process hooks, which are run in the same
jerojasro@336: directory that Mercurial was run in).
jerojasro@336: 
jerojasro@336: Hook parameters are passed to the hook as environment variables.  Each
jerojasro@336: environment variable's name is converted in upper case and prefixed
jerojasro@336: with the string ``\texttt{HG\_}''.  For example, if the name of a
jerojasro@336: parameter is ``\texttt{node}'', the name of the environment variable
jerojasro@336: representing that parameter will be ``\texttt{HG\_NODE}''.
jerojasro@336: 
jerojasro@336: A boolean parameter is represented as the string ``\texttt{1}'' for
jerojasro@336: ``true'', ``\texttt{0}'' for ``false''.  If an environment variable is
jerojasro@336: named \envar{HG\_NODE}, \envar{HG\_PARENT1} or \envar{HG\_PARENT2}, it
jerojasro@336: contains a changeset ID represented as a hexadecimal string.  The
jerojasro@336: empty string is used to represent ``null changeset ID'' instead of a
jerojasro@336: string of zeroes.  If an environment variable is named
jerojasro@336: \envar{HG\_URL}, it will contain the URL of a remote repository, if
jerojasro@336: that can be determined.
jerojasro@336: 
jerojasro@336: If a hook exits with a status of zero, it is considered to have
jerojasro@336: succeeded.  If it exits with a non-zero status, it is considered to
jerojasro@336: have failed.
jerojasro@336: 
jerojasro@336: \subsection{Finding out where changesets come from}
jerojasro@336: 
jerojasro@336: A hook that involves the transfer of changesets between a local
jerojasro@336: repository and another may be able to find out information about the
jerojasro@336: ``far side''.  Mercurial knows \emph{how} changes are being
jerojasro@336: transferred, and in many cases \emph{where} they are being transferred
jerojasro@336: to or from.
jerojasro@336: 
jerojasro@336: \subsubsection{Sources of changesets}
jerojasro@336: \label{sec:hook:sources}
jerojasro@336: 
jerojasro@336: Mercurial will tell a hook what means are, or were, used to transfer
jerojasro@336: changesets between repositories.  This is provided by Mercurial in a
jerojasro@336: Python parameter named \texttt{source}, or an environment variable named
jerojasro@336: \envar{HG\_SOURCE}.
jerojasro@336: 
jerojasro@336: \begin{itemize}
jerojasro@336: \item[\texttt{serve}] Changesets are transferred to or from a remote
jerojasro@336:   repository over http or ssh.
jerojasro@336: \item[\texttt{pull}] Changesets are being transferred via a pull from
jerojasro@336:   one repository into another.
jerojasro@336: \item[\texttt{push}] Changesets are being transferred via a push from
jerojasro@336:   one repository into another.
jerojasro@336: \item[\texttt{bundle}] Changesets are being transferred to or from a
jerojasro@336:   bundle.
jerojasro@336: \end{itemize}
jerojasro@336: 
jerojasro@336: \subsubsection{Where changes are going---remote repository URLs}
jerojasro@336: \label{sec:hook:url}
jerojasro@336: 
jerojasro@336: When possible, Mercurial will tell a hook the location of the ``far
jerojasro@336: side'' of an activity that transfers changeset data between
jerojasro@336: repositories.  This is provided by Mercurial in a Python parameter
jerojasro@336: named \texttt{url}, or an environment variable named \envar{HG\_URL}.
jerojasro@336: 
jerojasro@336: This information is not always known.  If a hook is invoked in a
jerojasro@336: repository that is being served via http or ssh, Mercurial cannot tell
jerojasro@336: where the remote repository is, but it may know where the client is
jerojasro@336: connecting from.  In such cases, the URL will take one of the
jerojasro@336: following forms:
jerojasro@336: \begin{itemize}
jerojasro@336: \item \texttt{remote:ssh:\emph{ip-address}}---remote ssh client, at
jerojasro@336:   the given IP address.
jerojasro@336: \item \texttt{remote:http:\emph{ip-address}}---remote http client, at
jerojasro@336:   the given IP address.  If the client is using SSL, this will be of
jerojasro@336:   the form \texttt{remote:https:\emph{ip-address}}.
jerojasro@336: \item Empty---no information could be discovered about the remote
jerojasro@336:   client.
jerojasro@336: \end{itemize}
jerojasro@336: 
jerojasro@336: \section{Hook reference}
jerojasro@336: 
jerojasro@336: \subsection{\hook{changegroup}---after remote changesets added}
jerojasro@336: \label{sec:hook:changegroup}
jerojasro@336: 
jerojasro@336: This hook is run after a group of pre-existing changesets has been
jerojasro@336: added to the repository, for example via a \hgcmd{pull} or
jerojasro@336: \hgcmd{unbundle}.  This hook is run once per operation that added one
jerojasro@336: or more changesets.  This is in contrast to the \hook{incoming} hook,
jerojasro@336: which is run once per changeset, regardless of whether the changesets
jerojasro@336: arrive in a group.
jerojasro@336: 
jerojasro@336: Some possible uses for this hook include kicking off an automated
jerojasro@336: build or test of the added changesets, updating a bug database, or
jerojasro@336: notifying subscribers that a repository contains new changes.
jerojasro@336: 
jerojasro@336: Parameters to this hook:
jerojasro@336: \begin{itemize}
jerojasro@336: \item[\texttt{node}] A changeset ID.  The changeset ID of the first
jerojasro@336:   changeset in the group that was added.  All changesets between this
jerojasro@336:   and \index{tags!\texttt{tip}}\texttt{tip}, inclusive, were added by
jerojasro@336:   a single \hgcmd{pull}, \hgcmd{push} or \hgcmd{unbundle}.
jerojasro@336: \item[\texttt{source}] A string.  The source of these changes.  See
jerojasro@336:   section~\ref{sec:hook:sources} for details.
jerojasro@336: \item[\texttt{url}] A URL.  The location of the remote repository, if
jerojasro@336:   known.  See section~\ref{sec:hook:url} for more information.
jerojasro@336: \end{itemize}
jerojasro@336: 
jerojasro@336: See also: \hook{incoming} (section~\ref{sec:hook:incoming}),
jerojasro@336: \hook{prechangegroup} (section~\ref{sec:hook:prechangegroup}),
jerojasro@336: \hook{pretxnchangegroup} (section~\ref{sec:hook:pretxnchangegroup})
jerojasro@336: 
jerojasro@336: \subsection{\hook{commit}---after a new changeset is created}
jerojasro@336: \label{sec:hook:commit}
jerojasro@336: 
jerojasro@336: This hook is run after a new changeset has been created.
jerojasro@336: 
jerojasro@336: Parameters to this hook:
jerojasro@336: \begin{itemize}
jerojasro@336: \item[\texttt{node}] A changeset ID.  The changeset ID of the newly
jerojasro@336:   committed changeset.
jerojasro@336: \item[\texttt{parent1}] A changeset ID.  The changeset ID of the first
jerojasro@336:   parent of the newly committed changeset.
jerojasro@336: \item[\texttt{parent2}] A changeset ID.  The changeset ID of the second
jerojasro@336:   parent of the newly committed changeset.
jerojasro@336: \end{itemize}
jerojasro@336: 
jerojasro@336: See also: \hook{precommit} (section~\ref{sec:hook:precommit}),
jerojasro@336: \hook{pretxncommit} (section~\ref{sec:hook:pretxncommit})
jerojasro@336: 
jerojasro@336: \subsection{\hook{incoming}---after one remote changeset is added}
jerojasro@336: \label{sec:hook:incoming}
jerojasro@336: 
jerojasro@336: This hook is run after a pre-existing changeset has been added to the
jerojasro@336: repository, for example via a \hgcmd{push}.  If a group of changesets
jerojasro@336: was added in a single operation, this hook is called once for each
jerojasro@336: added changeset.
jerojasro@336: 
jerojasro@336: You can use this hook for the same purposes as the \hook{changegroup}
jerojasro@336: hook (section~\ref{sec:hook:changegroup}); it's simply more convenient
jerojasro@336: sometimes to run a hook once per group of changesets, while other
jerojasro@336: times it's handier once per changeset.
jerojasro@336: 
jerojasro@336: Parameters to this hook:
jerojasro@336: \begin{itemize}
jerojasro@336: \item[\texttt{node}] A changeset ID.  The ID of the newly added
jerojasro@336:   changeset.
jerojasro@336: \item[\texttt{source}] A string.  The source of these changes.  See
jerojasro@336:   section~\ref{sec:hook:sources} for details.
jerojasro@336: \item[\texttt{url}] A URL.  The location of the remote repository, if
jerojasro@336:   known.  See section~\ref{sec:hook:url} for more information.
jerojasro@336: \end{itemize}
jerojasro@336: 
jerojasro@336: See also: \hook{changegroup} (section~\ref{sec:hook:changegroup}) \hook{prechangegroup} (section~\ref{sec:hook:prechangegroup}), \hook{pretxnchangegroup} (section~\ref{sec:hook:pretxnchangegroup})
jerojasro@336: 
jerojasro@336: \subsection{\hook{outgoing}---after changesets are propagated}
jerojasro@336: \label{sec:hook:outgoing}
jerojasro@336: 
jerojasro@336: This hook is run after a group of changesets has been propagated out
jerojasro@336: of this repository, for example by a \hgcmd{push} or \hgcmd{bundle}
jerojasro@336: command.
jerojasro@336: 
jerojasro@336: One possible use for this hook is to notify administrators that
jerojasro@336: changes have been pulled.
jerojasro@336: 
jerojasro@336: Parameters to this hook:
jerojasro@336: \begin{itemize}
jerojasro@336: \item[\texttt{node}] A changeset ID.  The changeset ID of the first
jerojasro@336:   changeset of the group that was sent.
jerojasro@336: \item[\texttt{source}] A string.  The source of the of the operation
jerojasro@336:   (see section~\ref{sec:hook:sources}).  If a remote client pulled
jerojasro@336:   changes from this repository, \texttt{source} will be
jerojasro@336:   \texttt{serve}.  If the client that obtained changes from this
jerojasro@336:   repository was local, \texttt{source} will be \texttt{bundle},
jerojasro@336:   \texttt{pull}, or \texttt{push}, depending on the operation the
jerojasro@336:   client performed.
jerojasro@336: \item[\texttt{url}] A URL.  The location of the remote repository, if
jerojasro@336:   known.  See section~\ref{sec:hook:url} for more information.
jerojasro@336: \end{itemize}
jerojasro@336: 
jerojasro@336: See also: \hook{preoutgoing} (section~\ref{sec:hook:preoutgoing})
jerojasro@336: 
jerojasro@336: \subsection{\hook{prechangegroup}---before starting to add remote changesets}
jerojasro@336: \label{sec:hook:prechangegroup}
jerojasro@336: 
jerojasro@336: This controlling hook is run before Mercurial begins to add a group of
jerojasro@336: changesets from another repository.
jerojasro@336: 
jerojasro@336: This hook does not have any information about the changesets to be
jerojasro@336: added, because it is run before transmission of those changesets is
jerojasro@336: allowed to begin.  If this hook fails, the changesets will not be
jerojasro@336: transmitted.
jerojasro@336: 
jerojasro@336: One use for this hook is to prevent external changes from being added
jerojasro@336: to a repository.  For example, you could use this to ``freeze'' a
jerojasro@336: server-hosted branch temporarily or permanently so that users cannot
jerojasro@336: push to it, while still allowing a local administrator to modify the
jerojasro@336: repository.
jerojasro@336: 
jerojasro@336: Parameters to this hook:
jerojasro@336: \begin{itemize}
jerojasro@336: \item[\texttt{source}] A string.  The source of these changes.  See
jerojasro@336:   section~\ref{sec:hook:sources} for details.
jerojasro@336: \item[\texttt{url}] A URL.  The location of the remote repository, if
jerojasro@336:   known.  See section~\ref{sec:hook:url} for more information.
jerojasro@336: \end{itemize}
jerojasro@336: 
jerojasro@336: See also: \hook{changegroup} (section~\ref{sec:hook:changegroup}),
jerojasro@336: \hook{incoming} (section~\ref{sec:hook:incoming}), ,
jerojasro@336: \hook{pretxnchangegroup} (section~\ref{sec:hook:pretxnchangegroup})
jerojasro@336: 
jerojasro@336: \subsection{\hook{precommit}---before starting to commit a changeset}
jerojasro@336: \label{sec:hook:precommit}
jerojasro@336: 
jerojasro@336: This hook is run before Mercurial begins to commit a new changeset.
jerojasro@336: It is run before Mercurial has any of the metadata for the commit,
jerojasro@336: such as the files to be committed, the commit message, or the commit
jerojasro@336: date.
jerojasro@336: 
jerojasro@336: One use for this hook is to disable the ability to commit new
jerojasro@336: changesets, while still allowing incoming changesets.  Another is to
jerojasro@336: run a build or test, and only allow the commit to begin if the build
jerojasro@336: or test succeeds.
jerojasro@336: 
jerojasro@336: Parameters to this hook:
jerojasro@336: \begin{itemize}
jerojasro@336: \item[\texttt{parent1}] A changeset ID.  The changeset ID of the first
jerojasro@336:   parent of the working directory.
jerojasro@336: \item[\texttt{parent2}] A changeset ID.  The changeset ID of the second
jerojasro@336:   parent of the working directory.
jerojasro@336: \end{itemize}
jerojasro@336: If the commit proceeds, the parents of the working directory will
jerojasro@336: become the parents of the new changeset.
jerojasro@336: 
jerojasro@336: See also: \hook{commit} (section~\ref{sec:hook:commit}),
jerojasro@336: \hook{pretxncommit} (section~\ref{sec:hook:pretxncommit})
jerojasro@336: 
jerojasro@336: \subsection{\hook{preoutgoing}---before starting to propagate changesets}
jerojasro@336: \label{sec:hook:preoutgoing}
jerojasro@336: 
jerojasro@336: This hook is invoked before Mercurial knows the identities of the
jerojasro@336: changesets to be transmitted.
jerojasro@336: 
jerojasro@336: One use for this hook is to prevent changes from being transmitted to
jerojasro@336: another repository.
jerojasro@336: 
jerojasro@336: Parameters to this hook:
jerojasro@336: \begin{itemize}
jerojasro@336: \item[\texttt{source}] A string.  The source of the operation that is
jerojasro@336:   attempting to obtain changes from this repository (see
jerojasro@336:   section~\ref{sec:hook:sources}).  See the documentation for the
jerojasro@336:   \texttt{source} parameter to the \hook{outgoing} hook, in
jerojasro@336:   section~\ref{sec:hook:outgoing}, for possible values of this
jerojasro@336:   parameter.
jerojasro@336: \item[\texttt{url}] A URL.  The location of the remote repository, if
jerojasro@336:   known.  See section~\ref{sec:hook:url} for more information.
jerojasro@336: \end{itemize}
jerojasro@336: 
jerojasro@336: See also: \hook{outgoing} (section~\ref{sec:hook:outgoing})
jerojasro@336: 
jerojasro@336: \subsection{\hook{pretag}---before tagging a changeset}
jerojasro@336: \label{sec:hook:pretag}
jerojasro@336: 
jerojasro@336: This controlling hook is run before a tag is created.  If the hook
jerojasro@336: succeeds, creation of the tag proceeds.  If the hook fails, the tag is
jerojasro@336: not created.
jerojasro@336: 
jerojasro@336: Parameters to this hook:
jerojasro@336: \begin{itemize}
jerojasro@336: \item[\texttt{local}] A boolean.  Whether the tag is local to this
jerojasro@336:   repository instance (i.e.~stored in \sfilename{.hg/localtags}) or
jerojasro@336:   managed by Mercurial (stored in \sfilename{.hgtags}).
jerojasro@336: \item[\texttt{node}] A changeset ID.  The ID of the changeset to be tagged.
jerojasro@336: \item[\texttt{tag}] A string.  The name of the tag to be created.
jerojasro@336: \end{itemize}
jerojasro@336: 
jerojasro@336: If the tag to be created is revision-controlled, the \hook{precommit}
jerojasro@336: and \hook{pretxncommit} hooks (sections~\ref{sec:hook:commit}
jerojasro@336: and~\ref{sec:hook:pretxncommit}) will also be run.
jerojasro@336: 
jerojasro@336: See also: \hook{tag} (section~\ref{sec:hook:tag})
jerojasro@336: 
jerojasro@336: \subsection{\hook{pretxnchangegroup}---before completing addition of
jerojasro@336:   remote changesets}
jerojasro@336: \label{sec:hook:pretxnchangegroup}
jerojasro@336: 
jerojasro@336: This controlling hook is run before a transaction---that manages the
jerojasro@336: addition of a group of new changesets from outside the
jerojasro@336: repository---completes.  If the hook succeeds, the transaction
jerojasro@336: completes, and all of the changesets become permanent within this
jerojasro@336: repository.  If the hook fails, the transaction is rolled back, and
jerojasro@336: the data for the changesets is erased.
jerojasro@336: 
jerojasro@336: This hook can access the metadata associated with the almost-added
jerojasro@336: changesets, but it should not do anything permanent with this data.
jerojasro@336: It must also not modify the working directory.
jerojasro@336: 
jerojasro@336: While this hook is running, if other Mercurial processes access this
jerojasro@336: repository, they will be able to see the almost-added changesets as if
jerojasro@336: they are permanent.  This may lead to race conditions if you do not
jerojasro@336: take steps to avoid them.
jerojasro@336: 
jerojasro@336: This hook can be used to automatically vet a group of changesets.  If
jerojasro@336: the hook fails, all of the changesets are ``rejected'' when the
jerojasro@336: transaction rolls back.
jerojasro@336: 
jerojasro@336: Parameters to this hook:
jerojasro@336: \begin{itemize}
jerojasro@336: \item[\texttt{node}] A changeset ID.  The changeset ID of the first
jerojasro@336:   changeset in the group that was added.  All changesets between this
jerojasro@336:   and \index{tags!\texttt{tip}}\texttt{tip}, inclusive, were added by
jerojasro@336:   a single \hgcmd{pull}, \hgcmd{push} or \hgcmd{unbundle}.
jerojasro@336: \item[\texttt{source}] A string.  The source of these changes.  See
jerojasro@336:   section~\ref{sec:hook:sources} for details.
jerojasro@336: \item[\texttt{url}] A URL.  The location of the remote repository, if
jerojasro@336:   known.  See section~\ref{sec:hook:url} for more information.
jerojasro@336: \end{itemize}
jerojasro@336: 
jerojasro@336: See also: \hook{changegroup} (section~\ref{sec:hook:changegroup}),
jerojasro@336: \hook{incoming} (section~\ref{sec:hook:incoming}),
jerojasro@336: \hook{prechangegroup} (section~\ref{sec:hook:prechangegroup})
jerojasro@336: 
jerojasro@336: \subsection{\hook{pretxncommit}---before completing commit of new changeset}
jerojasro@336: \label{sec:hook:pretxncommit}
jerojasro@336: 
jerojasro@336: This controlling hook is run before a transaction---that manages a new
jerojasro@336: commit---completes.  If the hook succeeds, the transaction completes
jerojasro@336: and the changeset becomes permanent within this repository.  If the
jerojasro@336: hook fails, the transaction is rolled back, and the commit data is
jerojasro@336: erased.
jerojasro@336: 
jerojasro@336: This hook can access the metadata associated with the almost-new
jerojasro@336: changeset, but it should not do anything permanent with this data.  It
jerojasro@336: must also not modify the working directory.
jerojasro@336: 
jerojasro@336: While this hook is running, if other Mercurial processes access this
jerojasro@336: repository, they will be able to see the almost-new changeset as if it
jerojasro@336: is permanent.  This may lead to race conditions if you do not take
jerojasro@336: steps to avoid them.
jerojasro@336: 
jerojasro@336: Parameters to this hook:
jerojasro@336: \begin{itemize}
jerojasro@336: \item[\texttt{node}] A changeset ID.  The changeset ID of the newly
jerojasro@336:   committed changeset.
jerojasro@336: \item[\texttt{parent1}] A changeset ID.  The changeset ID of the first
jerojasro@336:   parent of the newly committed changeset.
jerojasro@336: \item[\texttt{parent2}] A changeset ID.  The changeset ID of the second
jerojasro@336:   parent of the newly committed changeset.
jerojasro@336: \end{itemize}
jerojasro@336: 
jerojasro@336: See also: \hook{precommit} (section~\ref{sec:hook:precommit})
jerojasro@336: 
jerojasro@336: \subsection{\hook{preupdate}---before updating or merging working directory}
jerojasro@336: \label{sec:hook:preupdate}
jerojasro@336: 
jerojasro@336: This controlling hook is run before an update or merge of the working
jerojasro@336: directory begins.  It is run only if Mercurial's normal pre-update
jerojasro@336: checks determine that the update or merge can proceed.  If the hook
jerojasro@336: succeeds, the update or merge may proceed; if it fails, the update or
jerojasro@336: merge does not start.
jerojasro@336: 
jerojasro@336: Parameters to this hook:
jerojasro@336: \begin{itemize}
jerojasro@336: \item[\texttt{parent1}] A changeset ID.  The ID of the parent that the
jerojasro@336:   working directory is to be updated to.  If the working directory is
jerojasro@336:   being merged, it will not change this parent.
jerojasro@336: \item[\texttt{parent2}] A changeset ID.  Only set if the working
jerojasro@336:   directory is being merged.  The ID of the revision that the working
jerojasro@336:   directory is being merged with.
jerojasro@336: \end{itemize}
jerojasro@336: 
jerojasro@336: See also: \hook{update} (section~\ref{sec:hook:update})
jerojasro@336: 
jerojasro@336: \subsection{\hook{tag}---after tagging a changeset}
jerojasro@336: \label{sec:hook:tag}
jerojasro@336: 
jerojasro@336: This hook is run after a tag has been created.
jerojasro@336: 
jerojasro@336: Parameters to this hook:
jerojasro@336: \begin{itemize}
jerojasro@336: \item[\texttt{local}] A boolean.  Whether the new tag is local to this
jerojasro@336:   repository instance (i.e.~stored in \sfilename{.hg/localtags}) or
jerojasro@336:   managed by Mercurial (stored in \sfilename{.hgtags}).
jerojasro@336: \item[\texttt{node}] A changeset ID.  The ID of the changeset that was
jerojasro@336:   tagged.
jerojasro@336: \item[\texttt{tag}] A string.  The name of the tag that was created.
jerojasro@336: \end{itemize}
jerojasro@336: 
jerojasro@336: If the created tag is revision-controlled, the \hook{commit} hook
jerojasro@336: (section~\ref{sec:hook:commit}) is run before this hook.
jerojasro@336: 
jerojasro@336: See also: \hook{pretag} (section~\ref{sec:hook:pretag})
jerojasro@336: 
jerojasro@336: \subsection{\hook{update}---after updating or merging working directory}
jerojasro@336: \label{sec:hook:update}
jerojasro@336: 
jerojasro@336: This hook is run after an update or merge of the working directory
jerojasro@336: completes.  Since a merge can fail (if the external \command{hgmerge}
jerojasro@336: command fails to resolve conflicts in a file), this hook communicates
jerojasro@336: whether the update or merge completed cleanly.
jerojasro@336: 
jerojasro@336: \begin{itemize}
jerojasro@336: \item[\texttt{error}] A boolean.  Indicates whether the update or
jerojasro@336:   merge completed successfully.
jerojasro@336: \item[\texttt{parent1}] A changeset ID.  The ID of the parent that the
jerojasro@336:   working directory was updated to.  If the working directory was
jerojasro@336:   merged, it will not have changed this parent.
jerojasro@336: \item[\texttt{parent2}] A changeset ID.  Only set if the working
jerojasro@336:   directory was merged.  The ID of the revision that the working
jerojasro@336:   directory was merged with.
jerojasro@336: \end{itemize}
jerojasro@336: 
jerojasro@336: See also: \hook{preupdate} (section~\ref{sec:hook:preupdate})
jerojasro@336: 
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